slow network card

Hi,
I got my Fiber line installed about 2 months ago. The offer I pay for says 1Gbits/s down and 200Mbits up. Naturally, I've never even gotten close to those speeds. At first, when the guy did his thing, I didn't have an Ethernet cable on hand (despite being a network and IT student...I know...

Just had XFinity/Comcast out to my house for a service call. They discovered that my PC was 100mbps slower than all the other PCs on my home wired network. They said it was probably my network card which is a Realtek PCIe GBE Family Controller LAN Driver .
My home network consists of the...